The present invention relates to a gas governor apparatus and a gas piping system, and, more particularly, it relates to a gas governor apparatus suitable to regulate pressure of and control a flow rate of fluid in a piping installation for city gas and the like, and a gas piping system for effectively arranging such gas governor apparatus.
In conventional governor apparatus for regulating pressure of fluid such as city gas, as self-operated governor apparatuses, an apparatus comprising a diaphragm and a weight as disclosed in Japanese Patent Laid-Open No. 54-73327, and an apparatus comprising a pilot regulator and a sanders valve utilizing a rubber sleeve as disclosed in Japanese Patent Laid-Open No. 52-105330 have widely been used. Further, as direct drive governor apparatus, an apparatus comprising an outer casing, an inner casing and a screw mechanism, or an electronic governor apparatus wherein a valve is controlled by a solenoid and the like as disclosed in Japanese Patent Laid-Open No. 58-178115, or an apparatus comprising wherein a valve is driven through a screw mechanism by a drive source including a motor as disclosed in Japanese Patent Laid-Open No. 61-201972 has been used.
In addition, as a governor apparatus utilizing a shut-off valve, an apparatus comprising a cylinder and a spring and hydraulic pressure as disclosed in Japanese Patent Laid-Open No. 58-683 has been used.
However, in the conventional self-operated governor apparatuses, the former apparatus (as disclosed in Japanese Patent Laid-Open No. 54-73327), a governor body has double ports and a secondary pressure regulating mechanism is constituted by an intermediate pressure secondary governor, a low pressure secondary governor and an auxiliary ball including a diaphragm, and fluid pressure is adjusted by applying the weight onto a lever interconnected between the auxiliary ball and a main governor. While this governor apparatus provides a stable pressure regulation, such governor apparatus has disadvantages that an operating portion thereof is heavy, operation speed thereof is slow and the installation thereof requires a large space since the volume of the ball is large. On the other hand, in the latter apparatus (as disclosed in the japanese Patent Laid-Open No. 52-105330), a governor has a simple construction formed by assembling a pair of slitted frusto-conical grids in opposed relation and by covering a rubber sleeve onto the assembled grids and secondary pressure is controlled by a pilot regulator. While this governor apparatus has advantages that it is compact, light-weighted and noiseless, such apparatus has disadvantages that there is greater loss of pressure since the gas must push up the rubber sleeve when it flows and that the apparatus cannot be operated sufficiently when the difference between the primary pressure and the secondary pressure is small. Further, if the rubber sleeve is damaged, the apparatus will be unable to control. Further, in the conventional direct drive governor apparatus, it comprises the outer casing and the inner casing, a driving motor and a driving shaft are arranged within the inner casing, screw mechanisms are provided for a driven shaft and a valve body, and a flow passage is provided between the outer casing and the inner casing. While this governor apparatus has an advantage that it is compact and light-weighted, and that there is little loss of pressure, and that it is possible to adjust the pressure with high accuracy at high speed, such apparatus has disadvantages that, when fluid, other than the city gas, whose secondary pressure is higher than atmospheric pressure is controlled, the power consumption in the driving means is increased since a thrust force generated therein is not negligible. Further, if a driving system is troubled, since there is no provision of means for shutting-off the gas, energy shut-off valve must be further provided, with the result that a larger space is required for installation of the whole system.
On the other hand, the shut-off valve is structured to shut off the fluid by sliding the cylinder with utilizing the fluid pressure and has only a function to shut-off the fluid. It does not have a function to control the fluid pressure. Further, a case that the fluid is corrosive is not considered.